The present invention relates generally to less-invasive surgery of the cardiovascular system. More specifically, the invention relates to thoracoscopic devices and techniques for performing surgical procedures within the heart and great vessels while the heart is beating.
Tens of thousands of people are born each year with congenital defects of the heart. Some of the more common types of congenital cardiac defects include atrial septal defect (ASD), ventricular septal defect (VSD), and patent ductus arteriosis (PDA). An ASD is a hole in the cardiac septum between the left and right atria, while a VSD is a hole in the septum between the left and right ventricles. Patent ductus arteriosis is incomplete closure of the opening between the pulmonary artery and the aorta that is present during fetal development. These conditions may cause blood to abnormally shunt from the right side of the heart to the left side of the heart without being properly oxygenated in the lungs, so that the body tissues supplied by the blood are deprived of oxygen. In addition, blood in the left side of the heart may shunt back to the right side through the defect rather than being pumped into the arterial system, causing abnormal enlargement of the right chambers of the heart.
ASD""s, VSD""s and PDA can frequently be surgically repaired with significant success. Smaller defects may be reparable by simply suturing the defect closed, while larger defects may require a patch of polyester, expanded polytetrafluoroethylene, or a portion of the patient""s own pericardium to be sutured into the heart to cover and occlude the defect.
Ordinarily, such surgery is performed using open-chest techniques while the heart is under cardioplegic arrest and circulation is maintained by cardiopulmonary bypass. Using such techniques, a gross thoracotomy is created in order to gain access to the heart and great vessels, facilitating clamping and cannulation of the aorta for inducing cardioplegic arrest, and allowing instruments to be introduced into the chest cavity and into the heart to perform the surgical repair. The necessity of stopping the heart significantly heightens the risks attendant such procedures, particularly the risks of causing ischemic damage to the heart muscle, and of causing stroke or other injury due to circulatory emboli produced by aortic clamping and vascular cannulation. In addition, the creation of a gross thoracotomy produces significant morbidity and mortality, lengthens hospital stay and subsequent recovery, increases costs, and worsens the pain and trauma suffered by the patient. Moreover, many congenital defects are repaired in children under the age of ten years for whom the morbidity and mortality of open-chest surgery and cardioplegic arrest can be even greater than for older patients.
In an effort to avoid the necessity of grossly opening the chest and stopping the heart, a number of intravascular devices have been developed for repair of ASD""s, VSD""s, and PDA. For example, U.S. Pat. No. 3,874,388 to King et al. discloses an intravascular delivery catheter introduced intraluminally from a peripheral vein into the right side of the heart which can be used to position an artificial umbrella-like patch across a septal defect and to anchor the patch to the cardiac septum. Other intravascular delivery devices and artificial patches for the repair of septal defects can be seen in U.S. Pat. Nos. 5,334,217, 5,284,488, 4,917,089, 4,007,743, and PCT Application No. PCT/US92/10141.
While intravascular approaches to the repair of congenital defects may provide certain advantages, the most significant of which is the elimination of the need for gross thoracotomy and cardioplegic arrest, these techniques have suffered from a number of problems. One such problem is the difficulty in manipulating the artificial patches into position across a defect using only the proximal end of a long and flexible delivery catheter positioned through a tortuous arterial or venous lumen. Also problematic is the inadequacy of fixation of endovascularly-placed patches, creating a tendency of such patches to migrate or embolize after placement, which can allow blood to again shunt through the defect. In addition, once such a patch has been placed and the delivery catheter detached from the patch, relocating and repositioning the patch with the catheter is difficult, if not impossible, and may require open surgical correction. Moreover, in young children, the size of the peripheral vessels is extremely small, and damage to such vessels could have serious effects upon the growth of the child. Thus, the size of the devices which can be introduced through such vessels is greatly limited.
In addition to ASD, VSD, and PDA, various other types of cardiac disease also may be diagnosed and treated by intervention within the interior chambers of the heart. For example, some cardiac arrhythmias such as ventricular tachycardias, supraventricular tachycardias, and atrial fibrillation, may be diagnosed by obtaining access into an interior chamber of the heart and by performing electrophysiological mapping to identify abnormal conduction pathways. Once these abnormal conduction pathways are identified, in some cases the disease may be treated by ablating selected cardiac tissue using radiofrequency (RF) energy or a medical laser to eliminate the abnormal pathways. A number of endovascular approaches have been developed which attempt to allow intracardiac mapping and ablation using catheters introduced transluminally from peripheral vessels into the heart. Such devices are disclosed, for example, in U.S. Pat. Nos. 4,960,134, 4,573,473, 4,628,937, and 5,327,889. However, endovascular mapping and ablation devices suffer from many of the same problems suffered by endovascular septal defect repair devices, including a lack of control and precise positionability from the proximal end of these highly flexible and elongated devices, the significant size constraints of peripheral vessels, and the inability to position the devices in all potentially diseased sites within the heart.
What are needed, therefore, are devices and methods to enable the repair of ASD, VSD, PDA, and other congenital defects, as well as cardiac arrhythmias and other diseases of the heart, which eliminate the need for gross thoracotomy and cardioplegic arrest, but which overcome the forementioned problems with intravascular techniques. The devices and methods should facilitate a high level of control for precise manipulation within the heart. The devices and methods should produce a septal defect or PDA repair which is reliable and long-lasting, and should not be susceptible to migration, embolization, or reopening of a defect. The devices and methods for septal defect and PDA repair should allow the position of a repair patch to be inspected after initial placement and to be repositioned if necessary. Finally, the devices and methods should not risk damaging the peripheral vessels of the patient, nor should the size and configuration of the devices be limited by the size of the patient""s peripheral vessels.
The invention provides devices and methods that facilitate thoracoscopic access into the interior of the heart whether or not the heart is beating. This intracardiac access can be used to perform a variety of diagnostic and treatment procedures within the heart without the need for a gross thoracotomy or cardioplegic arrest. The invention provides devices and methods for the performance of a number of different procedures including the repair of ASD, VSD, PDA, and other cardiac abnormalities, electrophysiologic mapping and ablation for the treatment of cardiac arrhythmias, as well as a variety of other intracardiac procedures that can be performed thoracoscopically on a beating heart.
In a first aspect of the invention, a tubular access device is provided for accessing an interior chamber of a patient""s heart. The access device includes an elongated tubular body configured to extend percutaneously through an intercostal space between the ribs of the chest and through a muscular wall of the heart, and an inner lumen extending through the tubular body which provides an access channel into the heart. In an exemplary embodiment, the tubular access device has a length of at least 10 cm, and the inner lumen has a diameter of at least 5 mm. Preferably, the tubular access device is rigid to facilitate responsive and precise positionability from its proximal end.
In one embodiment, the access device includes means near a distal end thereof for sealing peripherally around a surrounding penetration in the muscular heart wall through which the access device is positioned. The sealing means may comprise one or a pair of inflatable balloons, a radially-expandable portion of the tubular body, or a flange at the distal end of the body. A purse string suture or other tissue-gathering means may be applied to the muscular heart wall surrounding the tubular body and tightened to prevent blood from flowing through the penetration around the access device.
The invention may further include an obturator positionable within an inner lumen of the tubular access device. The obturator may have means at its distal end for penetrating the muscular wall of the heart. The penetrating means may comprise a blade, radiofrequency electrode, or other type of cutting element. In a preferred embodiment, the obturator further includes means for selectively exposing the penetrating means, which may include a movable actuator for extending and retracting the cutting means from the distal end of the obturator.
The access device may include a hemostasis valve in the inner lumen to prevent blood flow out of the heart through the inner lumen, and to allow instruments to be introduced through the inner lumen while maintaining hemostasis in the inner lumen. The hemostasis valve may be disposed at either the proximal end or the distal end of the access device. Alternatively, when the access device is utilized in the lower-pressure right atrium, right ventricle, or left atrium, the access device may be positioned in a generally vertical orientation so that blood flow through the inner lumen is prevented by the pressure head of blood within the inner lumen being greater than the pressure in the cardiac chamber, eliminating the need for a hemostasis valve. With the access device positioned through an intercostal space and through a wall of the heart, a straight and relatively large channel directly into the interior of the heart is available for the introduction of devices for diagnostic and treatment procedures.
The invention further provides an assembly for visualization and access within a body cavity, and particularly, for visualization and access into a patient""s heart. The assembly includes a guide sleeve having a distal end, a proximal end, and a lumen therebetween. An endoscope is slidably positionable in the lumen, the endoscope having a shaft, a channel extending longitudinally through the shaft, at least one lens in the channel, and, usually, an eyepiece at the proximal end of the shaft. Alternatively, the endoscope may be of the type in which a video-imaging charge-coupled device (CCD) chip is mounted at the distal end of an elongated shaft and electronically coupled to a video processor which sends a video signal to a monitor. A transparent bulb is disposed at the distal end of the shaft outside of the channel and optically aligned with the lens. In this way, the transparent bulb serves to displace blood away from the distal end of the endoscope to allow the user to view the interior of the heart. Usually, the transparent bulb will be placed in contact with the intracardiac surface to be viewed, and the assembly then manipulated to inspect the surface or to identify a particular feature on the surface such as a septal defect.
The transparent bulb may be mounted to the distal end of the endoscope itself, or mounted to the end of a separate elongate sheath having a lumen in which the endoscope may be positioned with the distal end of the endoscope adjacent to the bulb. The use of a separate elongate sheath allows any of various commercially-available endoscopes to be utilized for intracardiac viewing without modification. The transparent bulb may also be mounted to a steerable endoscope having a deflectable end, or to a flexible sleeve in which a steerable endoscope may be positioned such that the sleeve may conform to the configuration of the endoscope.
In some embodiments, the transparent bulb is substantially rigid, being made of a clear, rigid polymer or glass. In other embodiments, the transparent bulb may be an expandable member such as an inflatable balloon, allowing the bulb to be collapsed into a small configuration for introduction into the heart, then expanded within the heart. The transparent bulb preferably has a transverse cross-sectional area larger than the transverse cross-sectional area of the shaft, and may further have a convex distal surface, facilitating the viewing of an area within the heart that is wider than that seen through the endoscope alone.
The guide sleeve has a length sufficient to reach an interior of a patient""s heart from outside the patient""s chest, usually being at least about 15 cm for pediatric use, or at least about 20 cm for adult use. The entire assembly is positionable in the heart through the inner lumen of the access device described above, or may be directly positioned in the heart through a penetration in a wall of the heart and sealed by means of a purse-string suture. The guide sleeve usually has an outer diameter of less than about 12 mm, and is preferably rigid to facilitate positioning the guide sleeve by manipulation of its proximal end. The guide sleeve may alternatively be flexible, with rigidity being provided by the placement of a rigid obturator or the endoscope itself through the guide sleeve.
The access and visualization assembly is useful in various medical procedures, but will find particular utility in intracardiac procedures in which the heart is to remain beating, such as septal defect repair. In use, the guide sleeve and endoscope are positioned in the heart through the inner lumen of the access device of the invention or directly through a penetration in the heart wall. The transparent bulb is positioned in contact with the intracardiac surface to be viewed, such as the interatrial septum. The proximal end of the assembly is then manipulated from outside the chest to inspect the surface and identify the location of treatment, such as a septal defect. Once located, the distal end of the guide sleeve is positioned through the defect, and the endoscope and transparent bulb are then withdrawn from the guide sleeve. The guide sleeve thereafter provides a conduit directly to the septal defect from outside the heart without requiring further use of the endoscope or other visualization devices to locate the defect. Defect repair devices may then be positioned through the guide sleeve directly to the septal defect to achieve the repair.
The invention also provides systems and methods for repairing atrial and ventricular septal defects through the guide sleeve of the above-described access and visualization assembly. The septal defect repair system includes a closure device for closing or occluding the septal defect, and a delivery device for introducing the closure device through the guide sleeve and into the interior of the heart.
In a first embodiment, the closure device comprises a patch that may be attached to the cardiac septum to cover and occlude the septal defect. The patch includes a collapsible frame, and a flexible patch material attached to the frame. The flexible patch material may be an artificial biocompatible material such as polyester or expanded polytetrafluorethylene, or a portion of the patient""s pericardium or other natural body membrane. The frame is configured to support the patch material at its outer edges in a generally flat configuration, and is sufficiently rigid to retain its shape against the pressure of blood within the heart, while having sufficient flexibility and resiliency to be collapsible for introduction through the inner lumen of the access device. In an exemplary embodiment the frame comprises a hub and a plurality of spokes extending radially outward from the hub. A circumferential wire or suture thread extending between the outer tips of the spokes may be provided to continuously support the outer edges of the patch. The hub is a rigid material such as stainless steel, is small enough to fit within the inner lumen of the access device, and is configured to be detachably coupled to the distal end of an delivery shaft (described below). The spokes are flexible, resilient wires of Nitinol(trademark) or other material exhibiting similar super-elastic characteristics. The patch may be mounted to the frame by sutures, heat welding, adhesive, or other means.
The patch includes a means for securing the patch to the cardiac septum. The securing means may comprise a second patch coupled to a central portion of the first patch and parallel thereto such that one patch may be positioned through the septal defect on the left side of the cardiac septum and the second patch positioned on the right side of the cardiac septum, with the outer edges of the two patches compressively engaging the cardiac septum between them. For example, in the hub and spoke embodiment describe above, two sets of spokes may be mounted to the hub and a patch mounted to each set of spokes so that the two patches are generally parallel to each other and spaced slightly apart. Alternatively, the securing means may comprise a plurality of flexible wire struts coupled to a central part of the frame such that the outer ends of the struts will compressively engage the cardiac septum on the side opposite that on which the patch is positioned. Like the patch, the securing means is collapsible to allow introduction through the inner lumen of the access device. To facilitate secure fixation to the septum, the frame or the securing means may include pins or spikes pointing generally perpendicular to the patch to partially penetrate the cardiac septum when the patch has been positioned across the defect, preventing migration of the patch.
The patch is introduced into the heart and positioned across the septal defect by means of a rigid delivery shaft which may be positioned through the guide sleeve. The delivery shaft includes an interior lumen or aperture at its distal end for receiving the patch and securing means in a collapsed configuration. The delivery shaft further includes a means for deploying the patch and the securing means, which may comprise a rod slidably disposed in a lumen through the delivery shaft. The rod includes means at its distal end for releasably coupling to the patch, such as a threaded extension which couples to a threaded hub in the patch frame. The rod may be advanced distally relative to the delivery shaft to deploy the patch from the aperture into the heart chamber on the side of the cardiac septum further away from the point of introduction, e.g., the left atrium if the device has been introduced into the heart through the right atrium. The patch is positioned against the septum, and the securing means is deployed on the side of the cardiac septum opposite the patch, e.g., the right atrium in the aforementioned case. The rod may then be decoupled from the patch and the delivery shaft is removed from the patient through the access device.
Advantageously, the delivery shaft and deployment means are configured to allow the patch to be re-collapsed and repositioned if the position of the patch is not satisfactory after initial deployment. In one embodiment, the rod is drawn proximally relative to the delivery shaft, whereby the patch is collapsed by engagement with the distal end of the delivery shaft. The patch securing means may be collapsed in a similar manner, or by a separate mechanism. In an exemplary embodiment, one or more wires or sutures extend through a lumen in the delivery shaft and are coupled to the securing means, e.g. to the outer ends of the spokes or struts of the securing means. By exerting tension on the wires, the securing means is drawn proximally into a collapsed configuration to allow it to be received in the aperture in the delivery shaft. This allows the patch and securing means to be drawn back into the aperture in the delivery shaft and redeployed at the desired position.
In an alternative embodiment, the septal defect closure device comprises a suturing device for applying at least one suture across the septal defect. The suturing device includes a rigid delivery shaft suitable for introduction through the guide sleeve, and a plurality of needle holders mounted to the delivery shaft for releasably holding at least two needles connected by a suture thread. The needle holders are movable between a contracted position suitable for introducing the needles through the septal defect into the cardiac chamber on the opposite side of the septum, and an expanded position in which the tips of the needles are aimed proximally toward the cardiac septum on opposing sides of the septal defect. In one embodiment, the needle holders are mounted on opposing sides of a balloon which may be deflated during introduction through a septal defect and then inflated to move the needles into the expanded position. The needle holders are then pulled proximally so that the needles penetrate the cardiac septum. A means is mounted to the delivery shaft for capturing the distal tips of the needles after penetrating the septum. For example, the needles may have barbed tips which engage a porous fabric disk slidably mounted to the delivery shaft. The needle capture means is retracted to draw the needles through the septum and out of the heart through the inner lumen of the access device. In this way, a plurality of sutures may be applied to the cardiac septum simultaneously. Knots may then be tied in the sutures extracorporeally, and, using a long-handled endoscopic knot-pusher, pushed through the access device into the heart so as to tighten the sutures and draw the opposing sides of the septal defect together.
In a further aspect of the invention, a method of locating an opening in a patient""s heart comprises the steps of positioning a visualization scope through a sleeve; positioning a distal end of the visualization scope into the heart through a penetration in a wall thereof; viewing the opening through the visualization scope; sliding the sleeve into the opening; and removing the visualization scope from the sleeve. The opening may comprise a septal defect, patent ductus arteriosus, or any of a variety of other intracardiac formations. The method may further include positioning the visualization scope in a sheath outside the heart such that a distal end of the visualization scope is adjacent to a transparent bulb on a distal end of the sheath; positioning the sheath in the heart through the sleeve; and viewing the opening through the transparent bulb.
If the opening is a septal defect or patent ductus arteriosus, the method may further include the steps of positioning a repair device through the sleeve while the sleeve is positioned through the opening; and closing the opening with the repair device. The repair device may comprise a patch which is secured across the opening, or a device for suturing the opening closed. In most embodiments, the visualization scope and the sleeve are positioned through an access device extending from outside the chest through the penetration in the wall of the heart.
While the method of the invention may find use in open-chest surgical procedures, it is preferably performed using thoracoscopic techniques, wherein the ribs and sternum remain intact and are not significantly retracted during each step of the procedure. Using such techniques, a working space may be created in the patient""s chest cavity by collapsing one of the patient""s lungs or using jet ventilation techniques. A viewing scope such as an endoscope or endoscopic surgical microscope may then be introduced through an intercostal space into the working space to view the exterior of the heart while the penetration is formed and the access device is introduced. The viewing scope may include a video camera to provide a video image of the heart for display on a monitor which can be viewed during the procedure. Alternatively, the heart may be viewed directly through a lens on the viewing scope or through a trocar sleeve positioned in an intercostal space. While it may be desirable to place the patient on cardiopulmonary bypass and arrest the heart during certain procedures, the invention facilitates the performance of a number of cardiac procedures while the heart is beating, without the need for cardiopulmonary bypass or cardioplegic arrest, and with significantly reduced risk of injury resulting from embolism.
Usually, the method will be performed in the right atrium, right ventricle, or left atrium, in which blood pressure is lower than in the left ventricle. Preferably, the access device is positioned in a vertical orientation, usually from a lateral side of the chest, with the distal end of the access device disposed in the interior chamber. In this way, the static pressure head of blood within the inner lumen is equal to the pressure within the interior chamber, preventing the flow of blood out of the interior chamber through the inner lumen. In an exemplary embodiment, small incisions and/or access ports are placed in the third, fourth, fifth, or sixth intercostal spaces on a lateral side of the chest. At least three such ports are usually required, one for introduction of the access device, one for introduction of a visualization device such as an endoscope, and one for introduction of other instruments for suturing, retraction, and other purposes.
In addition to the use of the assembly described above, visualization within the interior of the heart may be provided by various means. An ultrasonic probe may be positioned in the patient""s esophagus, on the surface of the patient""s chest, or in the chest cavity adjacent or in contact with the exterior of the heart to ultrasonically image the interior of the heart. An angioscope introduced into the heart endovascularly through a peripheral vessel may also be used for intracardiac visualization. Fluoroscopy is an additional technique for visualization.
The devices and methods of the invention may also be useful in other types of cardiac treatment procedures, including repair and replacement of cardiac valves, electrophysiological mapping and ablation, Cox xe2x80x9cmazexe2x80x9d surgical transection of the atrium, transmyocardial laser revascularization, pulmonary thrombectomy, intracardiac inspection, removal of growths, myxomas, neoplasms, hypertrophic obstructive cardiopmyopathy and vegetations, and other diagnostic and treatment procedures.
The nature and advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying exemplary drawings.